Tonight’s guest mentors are Sia (who ought to give really helpful tips on making eye contact with the audience) and Steven Van Zandt of Bruce Springsteen’s E Street Band. At the end of the night, the Top 4 will be standing, and will have performed twice, including one Sia song. If La’Porsha Renae isn’t among those moving on, the final season of Idol voters will have left the show with a very sorry swan song. She’s on track to win, and could provide the show with its best closing legacy.